1. Field of the Invention
The invention relates to an electrically erasable and programmable nonvolatile memory (EEPROM: Electrically Erasable Programmable Read Only Memory), in particular, a dual port EEPROM.
2. Description of the Related Art
A dual port EEPROM is an EEPROM having a plurality of memory banks each of which is accessible independently.
For example, a dual port EEPROM having first and second memory banks has first and second ports. This is configured so that the first memory bank becomes accessible by serially inputting a first control signal (a clock, address data, etc) to the first port and the second memory bank becomes accessible by serially inputting a second control signal (a clock, address data, etc) to the second port.
From a user's point of view, the dual port EEPROM is like one package in which a plurality of EEPROM are mounted, and realizes the independent and simultaneous use of these EEPROM for a plurality of separate systems. A dual port EEPROM is described in Japanese Patent Application publication No. Hei 11-306010.
As described above, in a conventional dual port EEPROM, a plurality of memory banks are independently accessed. Therefore, when data is to be written to each of the memory banks, a control signal need be inputted to each of the ports corresponding the memory banks, thereby causing a large number of processes.